关键词: 混合对流, 环流配置, 热力不稳定, 垂直风切变

Abstract:

Based on the aerological sounding and surface observation data, NCEP reanalysis data and Doppler radar data, the circulation configurations, environmental conditions and radar echoes of two mixed convective weather processes occurring in Hu’nan Province on 3 April and 19 April 2015 were analyzed contrastively. The results show that the synoptic type of the severe convective process on 3 April 2015 belonged to warm advection forced category, while that of the severe convective process on 19 April 2015 belonged to baroclinic frontogenesis category. The unstable stratifications with warm and wet in lower level and dry and cold in upper level, larger convective available potential energy, obvious sinking available potential energy, moderate above thermal instability and strong vertical wind shear in deep level were beneficial to the occurrence and  development of two mixed convection. However, the thermal and dynamical conditions of two convective processes were obviously different, the thermal instability of “4·19” process was stronger than that of “4·3” process, while the dynamical instability of “4·19” process was weaker than that of “4·3”process. Radar products showed that the hails of “4·3” process was mainly caused by the supercell storms, the thunderstorm gale was induced by linear convection storm, and the mixed rainfall echo of cumulus and stratus produced “train effect”, which led to the extreme heavy rain in the northeast of Hu’nan. The hails and thunderstorm gale of “4·19” process were caused by the supercell storm.

Key words: mixed convection, circulation configurations, thermal instability, vertical wind shear